Interpreting Torque Values

[chefyong]

Hello,

Can someone enlighten me how to interpret the following torque values.

M8 20 + 2Nm (14 +1.4 ft. lb)
M10 40 + 5Nm (29 +3.6 ft. lb)

On the first value, how does the 2Nm be applied to the 20Nm? and so with the second value, how does the 5 Nm be applied in reference to the 40Nm?

Do you torque 20 first then 2Nm? and 40 First then do 5 Nm for the second value?

Thanks

Manuel

[Bradical]

I'm not sure, but I am going to guess and see how close I can get!

I am thinking that the 14ft/lb is a lubricated torque spec, and 14ft/lb + 1.4ft/lb (15.4ft/lb) is the dry torque spec of those bolts. Don't know, but that's my guess. Those values are just general ones given for any otherwise unspecified M8 or M10 bolt on the car- obviously across a bunch of different applications. Some bolts or studs may be lubricated or not based on that.

Again, guessing!

[9FF]

Originally Posted by chefyong

Hello,

Can someone enlighten me how to interpret the following torque values.

M8 20 + 2Nm (14 +1.4 ft. lb)
M10 40 + 5Nm (29 +3.6 ft. lb)

On the first value, how does the 2Nm be applied to the 20Nm? and so with the second value, how does the 5 Nm be applied in reference to the 40Nm?

Do you torque 20 first then 2Nm? and 40 First then do 5 Nm for the second value?

Thanks

Manuel

I'll address the M8 bolt, the "+" is the tolerance and it means you can torque between 20 to 22Nm. So it has a +10% tolerance. The M10 bolt has a range likewise of between 40 to 45Nm.

You cannot apply a torque of 5Nm to a bolt that has been previously torqued to 40Nm, it simply will not register. Things like cylinder heads usually have INCREASING torque values that you apply in sequence like you are assuming.

Hope that makes sense ��

[chefyong]

yes, now it makes sense.

Thank you for your help